Hydroxy-functionalized porphycenes: Structure, spectroscopy, and electrochemistry

Toru Okawara, Masaaki Abe, Hisashi Shimakoshi, Yoshio Hisaeda

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9 Citations (Scopus)


A series of porphycenes bearing acetoxy and hydroxy groups at the meso-positions have been prepared and fully characterized: H2TPrPc- OH, [Ni(TPrPc-OH)], H2TPrPc-OAc, and [Ni(TPrPc-OAc)], where TPrPc-OH: 9-hydroxy- 2,7,12,17-tetrapropylporphycenato dianion and TPrPc-OAc: 9-acetoxy-2,7,12,17-tetrapropylporphycenato dianion. H2TPrPc-OH is structurally determined by single-crystal X-ray diffraction, showing the enol-form in the solid state. The introduction of the electron-donating hydroxy group to the meso-position decreases the HOMOLUMO gap by ca. 0.2 eV relative to the unsubstituted parent porphycene due to the remarkable destabilization of the HOMO level. This is experimentally confirmed by red shift of the Q band in the UVvis spectra (in CH2Cl2), negative shift of the E 1/2 (in 0.1M n-Bu4NPF6THF), and also supported by DFT calculations. In aqueous THF, an irreversible oxidation of H 2TPrPc-OH and [Ni(TPrPc-OH)] appears to be pH-dependent, with a negative Epa shift upon increasing the solution pH (in the region from 3.0 to 10.5) with slopes of -62 and -63mV per pH unit for H 2TPrPc-OH and [Ni(TPrPc-OH)], respectively, indicating the occurrence of {1H+/1e} proton-coupled electron transfer.

Original languageEnglish
Pages (from-to)718-728
Number of pages11
JournalBulletin of the Chemical Society of Japan
Issue number7
Publication statusPublished - 2011

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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